Hello! I would say that "scary close" is a way to say that something was so close that it was scary, so "scary" would be an intensifier in this case. For example: "Our near accident was scary close". The driver just managed to avoid an accident but it was so close that the driver and his passenger were very shaken up and were both frightened by the experience. I hope that helps!

I certainly understand what "scary close" means if someone said it to me, but is it proper? No. Everyone's explanation of what something means when it's so close that it's scary is correct. But "scary close" is not a known collocation to me, even though it's colloquial to begin with. (Don't get me wrong, I might have heard it, but if I have, it really hasn't been often enough to know.) I've commonly heard: "That was so close, it was scary." This example of "scary close" reminds me of other improper collocations. For example if someone in Canada is describing how hot it is today, they might joke that it's: "Mexico hot". There is no adverb to describe the verb 'hot', but rather a noun. It's meant to be funny. For "scary close" the verb is also described without an adverb, but instead with an adjective.

Good day Mohammad, "scary close" could stand as an alternative emphasis of a statement that expresses the lack of distance between a subject and an object so that the subject if frightened by it. In other words, "scary close" and "so close that (it) is scary" are relatively speaking equivalent in their meanings. I would avoid using these types of slang-ish expressions as they might and will affect the clarity of your speech. Thank you for your question. ----- If you have more questions, I will be more than happy to answer them on a private one to one lessons that I hold as a teacher on Italki. Sincerely, H.Kirishchyan

Interesting examples! Thanks a lot Fergus!

It is an intensifier, and it literally means "scarily", "disconcertingly", or "unexpectedly", depending on the context. It is US slang, and not "correct" English, and only used informally. I guess that it is a contraction of 'scarily', because, like other intensifiers, it functions as an adverb. You can use it with any adjective, depending on the context and meaning. For example: "Your kid is talented at math. Like, scary talented" "We started wrestling, and the girl was strong. I mean scary strong." Or this definition from Urban Dictionary dot com. scary: extremely; very, very "He's a scary good cook."